How to add , on the end of eatch clone, but not the last one.

e.g: (clones 3: me1, me2, me3) and not (clones 3: me1, me2, me3,)

Code:
on ^!*:join:#:{
  if %join.clone.scan == on {
    var %x_match = ( $+ $ialchan($address($nick,2),#,0) clone $+ $iif($ialchan($address($nick,2),#,0) > 1,s) $+ :
    var %x = $ialchan($address($nick,2),#,0) , %nicks
    if (%x > 1) { 
      while (%x) { %nicks = %nicks $ialchan($address($nick,2),#,%x).nick | dec %x }
    }
    %xnicks = %nicks $+ )
    if $me !isin %xnicks {
      echo -ltc join # * $nick ( $+ $address $+ ) has joined # 5 $+ $iif( $ialchan($address($nick,2),#,0) > 1 , %x_match %xnicks )
      haltdef
    }
  }
}